DE1602116B2 - PROCESS FOR PRODUCING SEAMLESS OR WELDED STEEL PIPES - Google Patents

Description

The invention relates to a method for producing seamless or welded steel pipes by cold pilgrimages.

It is known (German Patent 502155), seamless tubes from a hollow block in the way to produce that one breaks the hollow block obtained by centrifugal casting into pieces and the individual Pieces first rolled warm in a pilger mill and in the same heat or after subsequent reheating, finish-rolled in a duo-pass mill. It is also according to this publication State of the art, dividing a hollow block into pieces by the pilgrim method, and reheating these pieces and finish rolling over a mandrel in a pass mill.

It is also known in the manufacture of pipes by cold pilgrims that cold pilgrims are involved followed by cold deformation, namely in the form of cold drawing (German patent application K 12 351 Ib / 7a, published on May 8, 1952). Cold drawing, like cold pilgrimage, is only relatively permissible to achieve low production figures per hour. It is for this reason that the procedure is known remained limited to the production of steel tubes from high to medium alloyed steels.

In order to achieve larger productions per unit of time even with the cold pilgrimage, a subdivision is made the entire cold deformation in cold pilgrims and stretch reduction suggested, with avoidance thickening of the pipe ends that occurs in this case and thus relatively high ones to avoid Waste by longitudinal displacement of the conical pilgrim thorn in the course of the cold pilgrimage process, namely at its beginning and at its end, a pipe workpiece with at its ends to a length of about 1 m less wall thickness than in the rest of the pipe area is generated.

It is known to avoid the thickening of the pipe end that occurs during stretch reduction to use a pipe workpiece with a wall thickness that is thinner at its ends than in the rest of the pipe area (German Patent 521 444) and it is also known by cold pilgrims at appropriate Longitudinal displacement of the conical dome Pipes with changing wall thickness, especially with pipe ends to manufacture with a smaller wall thickness (German Patent application ρ 37 681 Ib / 7a, issued on June 16, 1954, and German magazine »Stahl und Eisen«, 1954, No. 14, p. 900).

However, it is not known about the new combination of cold pilgrims and stretch reduction carry out the cold pilgrimage in such a way that this already reduces the proportions of the subsequent stretching reduction are taken into account, so that a method advantageous in every direction with excellent Products is obtained. It must be taken into account that the state of the art mentioned announced to the expert world many years before the filing date of the present invention and was thus available to her without being evaluated for the purposes of the invention.

The method according to the application can be used for both seamless and welded steel pipes use. For the further processing of welded steel pipes, the suggested combination is of great importance. The weld seam is made by the cold pilger process and the downstream Cold reduction process and influenced very favorably by the required annealing treatments. The strong cold deformation results in a homogenization of the whole. Pipe cross-section a, the is practically equivalent to eliminating the weld seam.

The proposed combination is characterized by particularly economical material consumption. Since the system works without drawing benches, large lengths of pipe can be processed cold without pulling. The production of pull rods always means a loss of material and a disruption of the production process.

In the drawing, a cold pilger mill is shown schematically in Fig. 1, in A b b. 2 a special roller calibration is shown and in the A b b. 3 and 4 two embodiments of the invention Plant shown.

A b b. 1 shows the hot-rolled tube 1, which over the conical mandrel 2 by the oscillating Roller 3 is extended to the desired finished pipe 4.

The rollers according to Fig. 2 have a conical caliber of about 160 °, which is so far at the end of the stroke is opened so that there is no contact with the workpiece. In this position of the rollers to the workpiece the workpiece is given a small feed of about 8 to 10 mm. The advanced material is then stretched out in a known manner to form the finished pipe.

With regard to the dimensions, it is suggested, for example, a thick-walled tube of about 100 mm outer diameter and 7 mm wall on 7 m length, which is easy and very economical on rolling mills or hot-pressing can be produced by cold pilgrimage to a tube dimension of 76 mm to bring external diameter at 2.2 mm wall and about 30 m length. After stress relief annealing can this tube by cold rolling in the aforementioned three-roll cold reducing mill without Inner mandrel brought to the dimension 40 mm outer diameter with 2.2 mm wall and 57 m length will.

Looking at the A b b. 3 and 4, then in A b b. shown a plant in which four cold pilger rolling

works 5, 6, 7, 8 initially work on a roller table 9, from which the tubes via an oven 10 to another roller table 11, which feeds them to the cold reducing mill 12. The second Embodiment of a system according to A b b. 4 cold pilger mills 13,14,15,16 work on two Roller tables 17, 18. From there, the cold pilgrim tubes pass through ovens 19, 20 to a transverse roller table 21 and finally into the cold reducing mill 22.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Process for the production of seamless or welded steel pipes by cold pilgrims and subsequent cold working, characterized in that the further cold working takes place by stretch-reducing rollers and to avoid thickening of the pipe ends by moving the conical pilgrim mandrel lengthways at the beginning and end of the cold pilgrimage process into a 'pipe workpiece with a length of about 1 m shorter at its ends Wall thickness than in the rest of the pipe area is generated.